Investigators described it as a brutal, stubborn fire that consumed a boiler room and a chapel before it was put out, CBS 2’s Dave Carlin reported.

Students and staff were gone for the day when flames shot into the sky over Monsignor Scanlan. The fire gutted the boiler room where it started, left a chapel in ruins, and heavily damaged a science lab.

“It’s heartbreaking in a way. We wouldn’t expect this kind of thing to happen at our school,” sophomore Alexis Natal said.

Assistant Fire Chief William Seeling described a challenge for firefighters.

“Old wood frame building with all the problems associated with that. hidden spaces, once the fire starts traveling it’s a job to keep up with it,” Seeling said.

Joshua Torres told CBS 2’s Carlin that he witnessed the fire not long after it started. Torres came to campus with a friend to retrieve a phone that he had left behind after a mid term exam earlier in the day.

“I walked, the smoke you could smell it but I watched. It was terrifying so we just ran out,” He said.

Firefighters were met with towering flames and thick smoke. Five firefighters were injured but expected to recover.

The cause of the fire is unknown.

Classes are not scheduled for Monday, but midterms were planned for Tuesday and regular classes were supposed to resume on Wednesday. There was no word on how the fire would impact that schedule.